Mechanical Properties of Support Forms for Fault Fracture Zone in Subsea Tunnel

Subsea tunnels crossing a fault fracture zone have been a key issue for tunnel construction. Low rock mass strength in the fault fracture zone, poor self stabilization of the broken surrounding rock and complex geological conditions associated with the emergence of soft rock may easily cause geological disasters such as a collapse and a great deal of water intrusion during construction. This paper used Flac3D to establish a model of the regional fault zone stratum and a tunnel and to simulate tunnelling excavation, combined with a section of fault fracture zone, as well as preliminarily designed support methods and various parameters for the Xiamen Haicang tunnel. Utilizing numerical simulations of the different support methods and different support parameters, we compare the characteristics of the plastic zone, the surrounding rock deformation, and the stress distribution of the rock surrounding the tunnel to determine a suitable optimization of the tunnel support scheme that provided the basis for the field construction.